In a vehicle in which regenerative braking is conducted, when braking slip of the wheel which is applied with regenerative braking force becomes excessive, so called “braking force replacement” is carried out prior to the braking force control by an anti-skid control (ABS control). That is, regenerative braking force is replaced by friction braking force by decreasing regenerative braking force to 0 and gradually increasing friction braking force. When a condition for initiating the anti-skid control after completion of the braking force replacement, the braking slip of the wheel is alleviated by decreasing and increasing the friction braking force by the anti-skid control in accordance with the braking slip.
In the braking force replacement, in the event where the friction braking force is increased from 0, the friction braking force does not increase at once after a command to increase the friction braking force is outputted, and the increase rate of the friction braking force assumes lower than that of the command. The cause for the above includes a period of time which is required for the pressure in a wheel cylinder to actually increase after the supply of brake fluid to the wheel cylinder is initiated by a brake actuator, a delay in response of the brake actuator, knock back and the like.
If the braking force of the whole of a vehicle is decreased due to the delay in increasing of the friction braking force during the braking force replacement, the deceleration of the vehicle decreases, which may cause the occupants in the vehicle to feel discomfort. In the Japanese Patent Laid-Open Publication No. 2004-142687, for example, as a configuration to cope with the above problem, it is proposed to compensate the insufficient quantity of the braking force due to the delay in increasing of the friction braking force with regenerative braking force. According to the configuration described in the Laid-Open Publication, a risk can be reduced that the braking force of the whole of a vehicle becomes insufficient during the braking force replacement and the deceleration of the vehicle decreases due to the insufficiency.